The project utilizes new diagnostic methods and prototypic treatments in three controlled clinical trials attempting to better characterize the pathophysiology of chronic facial pain. The first study is a double-blind clinical evaluation of the effect of iontophoretically applied dexamethasone, in comparison to placebo, for temporomandibular joint pain. Subjects determined to have internal derangement of the temporomandibular joint complete a battery of analgesic and psychologic questionnaires prior to drug administration. Mandibular range of motion (including vertical, lateral, and protrusive movements) are assessed. Subjects randomly receive either 0.4% dexamethasone in a vehicle of 4% lidocaine or saline placebo by iontophoretic administration. Approximately 95% of the projected sample of 60 subjects have completed the protocol. In the second study, subjects are diagnosed into one of four groups as determined by clinical signs and symptoms: localized masticatory myalgia, fibromyalgia, polymyalgia rheumatica and normal controls. Magnetic resonance spectroscopy (MRS) is also performed and interpreted by a radiologist blind to diagnoses. After collection of baseline palpation and MRS data, subjects are asked to chew at a rate of approximately 80 chewing strokes per minute in order to stress the masticatory musculature. MRS is performed following the exercise in the same manner as the baseline measurements. Differences between groups in exercise tolerance, tissue pH, or phosphate energy metabolism may provide insight into pathophysiologic processes contributing to chronic facial pain of muscular origin. A third study uses pressure algometry to assess reproducibility of pain pressure thresholds in masseter and temporalis muscles in patients with chronic myogenic facial pain and in normal controls. These data show that patients and controls display site-specific reproducibility over time.